In the first case, the target CCD location is determined from its KIC right ascension and declination coordinates by evaluating so-called “motion polynomials,” and averaging over the in-transit cadences in the given quarter. Motion polynomials are computed in PA, and represent robust two-dimensional polynomial fits to the PRF-based centroids of 200 gold standard (Kp \(\sim 12\)  and relatively uncrowded) targets on each module output; essentially these polynomials provide a cadence by cadence mapping between the sky and the focal plane [1]}. The gold standard targets are the brightest for which the CCDs do not saturate, and therefore provide the highest fidelity centroids to determine the sky to focal plane mapping.
